What is Function Generator : Circuit Diagram & Its Specifications

Function Generator is a type of instrument which is used to generate different types of waveforms like sinusoidal, triangular, rectangular, square waveforms. The different types of waveforms have different frequencies which can be generated by using the instrument as a function generator. This generator generates five types of waveforms, they are sine, square, saw-tooth, triangle, and rectangle waveforms. There are two types of function generators they are analog and digital. The frequencies provided by this generator is up to 20 MHz. A brief explanation of this generator is discussed in this article along with the circuit diagram and block diagram.

What is Function Generator?

Definition: The function generator is defined as a type of device which produces various types of waveforms as its output signals. The common waveforms generated by this generator are sine wave, square wave, triangular wave, and sawtooth waves. The waveforms of these frequencies may be adjusted from hertz to a hundred kHz. This generator is considered as the most versatile instrument in the electrical and electronics laboratory because the waveforms generated by this generator have applications in different areas.

The analog function generator and digital function generators are types of function generators. The advantages of an analog generator are cost-effective, simple to use, flexibility, amplitude and frequencies are adjustable. The advantages of digital generators are of high accuracy and stability. The main disadvantages of this digital generator are complicated and costly.

Function Generator Block Diagram

The block diagram of function generator contains various components they are frequency control network, constant current supply source 1, constant current supply source 2, integrator, voltage comparator multivibrator, capacitor, a resistance diode shaping circuit, and two output amplifiers. The block diagram of this generator is shown in the below figure.

Function Generator Block Diagram
Function Generator Block Diagram

The frequencies can be controlled by varying the current magnitude. The two constant-current supplies will change the frequency of the output signal. The output waveforms generated by this generator are sinusoidal, triangular, and square. The frequency range of these waveforms ranges from 0.01 Hz to 100 kHz. The frequency control network controls the frequency on the front panel of this generator, and there is a knob called frequency control. The frequency of the o/p waveforms can be changed by using this knob & varying the frequency.

The frequency control network provides the voltage, and this voltage goes to regulate the two constant current supply sources like upper and lower. The first output voltage of constant current supply can be increased linearly with the time, whereas the lower current source provides a voltage to change the output voltage of the integrator which will decrease linearly with time. The output voltage of the integrator due to the upper current source is expressed.


When the slope of the o/p voltage increases or decreases then the constant current supply source 1 will be increases or decreases. The lower constant current source two supplies reverse control to the integrator, and due to this reverse current, the output voltage of the integrator decreases linearly with the time. The output of the comparator provides a square wave which has the same frequency as the output voltage. The resistance diode network changes the triangle waveform slope as its amplitude produces and changes a sine waveform with a <1% distortion. The output waveforms of this generator are shown below.

Output Waveforms of Function Generator
Output Waveforms of Function Generator

In this way, the three types of waveforms are produced by this generator which are having different frequencies. The clock source, timing margin test, dc power supply test, testing audio DAC are some of the applications of a function generator.

Function Generator Products

The different type of function generators products are shown in the below table

S.NOModel No.FrequencyBrandModel NumberWaveforms
1MetroQ MTQ 201T2Hz to 200KHzMetroQMTQ 201TSine, Square and Triangle Wave
2Audio Frequency Function Generator0.2Hz to 200 kHzASICOAE 512Sine, Square, Triangle Waves
3Metravi FG-50001Hz— 5MhzMetraviFG-5000Sine, Triangle, Square, Ramp, Pulse Waves
4MetroQ MTQ 10010.1Hz to 1MHzMetroQMTQ 1001Sine, Square and Triangle and TTL Output
5HTTC FG-20020.2Hz ~ 2MHzNAAFIEFG-2002Sine Wave, Square Wave, and Triangle Wave

Function Generator Circuit Diagram with LM324 Op-Amp

The LM324 is a 14-pin integrated circuit, the circuit diagram of the function generator with LM324 is shown below. The components required for this circuit are LM324 op-amp chip, two 10kΩ resistors, four 100kΩ resistors, 22kΩ resistor, 220kΩ resistor, 1μF ceramic capacitor, 33 nF ceramic capacitor, 10nF capacitor, and 100k Ω potentiometer. The circuit contains three operational amplifiers, the first operational amplifier generates the square wave, the second operational amplifier generates the triangle wave output, and the third operational amplifier generates the sine wave output.

Function Generator Circuit Diagram with LM324 Op-Amp
Function Generator Circuit Diagram with LM324 Op-Amp

The pin diagram of the LM324 IC is shown below.

LM324 IC Pin Diagram
LM324 IC Pin Diagram

The LM324 is an integrated chip that consists of 14 pins. The pin 1, 7,8,14 are the output pins, pin 2,6,9,4 are the inverting input pins, and pin 3,5,10, 12 are the non-inverting input pins, pin 4 is the Vcc (power supply), and pin 11 is the ground.


The general-purpose functional generator specifications are shown below

  • This generator produces five types of waveforms
  • The wide range of frequencies are generated by this generator
  • For an analog generator, the frequency stability is 0.1 % per hour
  • The maximum sine wave distortion for analog generators is about 1%
  • The modulations AM (Amplitude Modulation), FM (Frequency Modulation), or PM (Phase Modulation) are supported
  • The amplitude output is up to 10V

Safety Precautions

Some of the safety precautions of function generator are

  • Use proper voltage setting
  • Provide proper ventilation
  • Don’t operate at high frequency and pressure


1). What is the difference between a signal generator and a function generator?

The function generator generates multiple waveforms like a sine wave, sawtooth wave, triangle waves, rectangle waves, and square waveforms, but in the case of signal generators, only sine waves are generated.

2). What is the logic function generator?

The logic function generator is one type of generator which generates binary signals.

3). How do generators work?

The generator converts the energy from mechanical to electrical and it works on the electromagnetic induction principle.

4). Where is the function generator used?

The function generators used to generate various waveforms like sine waveform, saw tooth waveform, etc.

5). What are the types of function generators?

There are two types of generators they are analog and digital function generators.

In this article, the overview of function generator working, circuit diagram with LM324 operational amplifier, block diagram, pin diagram of LM324 operational amplifier, output waveforms of function generators are discussed. Here is a question for you what is the frequency range of function generator?

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